func ExampleMonitor() {
const (
frequency = 44100
format = openal.FormatStereo16
captureSize = 512
buffersCount = 10
)
mic := openal.CaptureOpenDevice("", frequency, format, frequency*2)
mic.CaptureStart()
defer mic.CloseDevice()
device := openal.OpenDevice("")
defer device.CloseDevice()
context := device.CreateContext()
context.Activate()
defer context.Destroy()
source := openal.NewSource()
source.SetLooping(false)
defer source.Stop()
buffers := openal.NewBuffers(buffersCount)
samples := make([]byte, captureSize*format.SampleSize())
start := time.Now()
for time.Since(start) < time.Second { // play for 1 second
if err := openal.Err(); err != nil {
fmt.Println("error:", err)
return
}
// Get any free buffers
if prcessed := source.BuffersProcessed(); prcessed > 0 {
buffersNew := make(openal.Buffers, prcessed)
source.UnqueueBuffers(buffersNew)
buffers = append(buffers, buffersNew...)
}
if len(buffers) == 0 {
continue
}
if mic.CapturedSamples() >= captureSize {
mic.CaptureTo(samples)
buffer := buffers[len(buffers)-1]
buffers = buffers[:len(buffers)-1]
buffer.SetData(format, samples, frequency)
source.QueueBuffer(buffer)
// If we have enough buffers, start playing
if source.State() != openal.Playing {
if source.BuffersQueued() > 2 {
source.Play()
}
}
}
}
fmt.Println(source.State())
// Output: Playing
}
func NewPlayer(sampleRate, channelNum, bytesPerSample int) (*Player, error) {
d := openal.OpenDevice("")
if d == nil {
return nil, fmt.Errorf("driver: OpenDevice must not return nil")
}
c := d.CreateContext()
if c == nil {
return nil, fmt.Errorf("driver: CreateContext must not return nil")
}
// Don't check openal.Err until making the current context is done.
// Linux might fail this check even though it succeeds (#204).
c.Activate()
if err := openal.Err(); err != nil {
return nil, fmt.Errorf("driver: Activate: %v", err)
}
s := openal.NewSource()
if err := openal.Err(); err != nil {
return nil, fmt.Errorf("driver: NewSource: %v", err)
}
p := &Player{
alDevice: d,
alSource: s,
alBuffers: []openal.Buffer{},
sampleRate: sampleRate,
alFormat: alFormat(channelNum, bytesPerSample),
}
runtime.SetFinalizer(p, (*Player).Close)
bs := openal.NewBuffers(maxBufferNum)
const bufferSize = 1024
emptyBytes := make([]byte, bufferSize)
for _, b := range bs {
// Note that the third argument of only the first buffer is used.
b.SetData(p.alFormat, emptyBytes, int32(p.sampleRate))
p.alBuffers = append(p.alBuffers, b)
}
p.alSource.Play()
return p, nil
}
func initialize() {
// Creating OpenAL device must be done after initializing UI. I'm not sure the reason.
ch := make(chan struct{})
go func() {
runtime.LockOSThread()
device := openal.OpenDevice("")
context := device.CreateContext()
context.Activate()
if alErr := openal.GetError(); alErr != 0 {
log.Printf("OpenAL initialize error: %d", alErr)
close(ch)
// Graceful ending: Audio is not available on Travis CI.
return
}
audioEnabled = true
sources := openal.NewSources(MaxChannel)
close(ch)
const bufferSize = 2048
emptyBytes := make([]byte, bufferSize)
for _, source := range sources {
// 3 is the least number?
// http://stackoverflow.com/questions/14932004/play-sound-with-openalstream
const bufferNum = 4
buffers := openal.NewBuffers(bufferNum)
for _, buffer := range buffers {
buffer.SetData(openal.FormatStereo16, emptyBytes, SampleRate)
source.QueueBuffer(buffer)
}
source.Play()
if alErr := openal.GetError(); alErr != 0 {
panic(fmt.Sprintf("OpenAL error: %d", alErr))
}
}
for {
oneProcessed := false
for ch, source := range sources {
processed := source.BuffersProcessed()
if processed == 0 {
continue
}
oneProcessed = true
buffers := make([]openal.Buffer, processed)
source.UnqueueBuffers(buffers)
for _, buffer := range buffers {
b := make([]byte, bufferSize)
copy(b, loadChannelBuffer(ch, bufferSize))
buffer.SetData(openal.FormatStereo16, b, SampleRate)
source.QueueBuffer(buffer)
}
if source.State() == openal.Stopped {
source.Rewind()
source.Play()
}
}
if !oneProcessed {
time.Sleep(1 * time.Millisecond)
}
}
}()
<-ch
}
